Hollow box support

ABSTRACT

A hollow box support comprising a reinforced lower structural element at least partially formed of concrete, and a reinforced upper structural element at least partially formed of concrete, both said upper and lower elements being separately fabricated. The upper and lower elements are rigidly connected with one another along their lengthwise extending sides connection layers, and viewed in cross-section, the wall of the lower element extends towards the outside in ascending fashion in the direction of and toward the upper element. The connection layers are defined by a respective essentially upright concrete connection layer each of which bears against the associated lengthwise extending sides of both the upper element and the lower element. Reinforcement means incorporating reinforcement elements are provided for the upper and lower elements and extend in the transverse direction of the hollow box support. Such reinforcement means extend into the concrete connection layers and overlie or overlap one another at such location, and wherein the reinforcement means located at the lower element extends neighboring the outside wall of the lower element.

Schmitter Feb. 12, 11974 1 HOLLOW BOX SUPPORT [76] Inventor: Adolf Schmitter, Kranstrasse,

Altstatten, Switzerland 22 Filed: Oct. 29, 1971 21 Appl. No.: 193,723

[30] Foreign Application Priority Data Nov. 3, 1970 Switzerland 16283/70 Jan. 27, 1971 Switzerland 1171/71 [52] US. Cl 52/600, 52/87, 52/223, 52/378, 52/606, 52/723, 404/1 [51] Int. Cl. E040 3/00, E04b l/16, E046 3/34 [58] Field of Search 52/87, 80, 177, 223 R, 224, 52/250, 723, 251', 731, 378; 14/6, 17; 94/4 Primary Examiner-John E. Murtagh Assistant Examiner-John R. Masterman Attorney, Agent, or Firm-Ladas, Parry, Von Gehr,

Goldsmith & Deschamps 57 ABSTRACT A hollow box support comprising a reinforced lower structural element at least partially formed of con crete, and a reinforced upper structural element at least partially formed of concrete, both said upper and lower elements being separately fabricatedv The upper and lower elements are rigidly connected with one another along their lengthwise extending sides connection layers, and viewed in cross-section, the wall of the lower element extends towards the outside in ascending fashion in the direction of and toward the upper element. The connection layers are defined by a respective essentially upright concrete connection layer each of which bears against the associated lengthwise extending sides of both the upper element and the lower element. Reinforcement means incorporating reinforcement elements are provided for the upper and lower elements and extend in the transverse direction of "the hollow box support. Such reinforcement means extend into the concrete connection layers and overlie or overlap one another at such location, and wherein the reinforcement means located at the lower element extends neighboring the outside wall of the lower element.

1 Claim, 4 Drawing Figures HOLLOW BOX SUPPORT The method of fabrication of such hollow box supports comprises fabricating the lower element in an open form and providing a pre-fabricated upper element. The prefabricated upper element is placed upon the lower element, and the connection layers are molded between such upper and lower elements.

BACKGROUND AND SUMMARY OF THE INVENTION The present invention broadly relates to hollow boxtype construction components, and more specifically to a new and improved hollow box support or girder formed of separately fabricated lower and upper reinforced structural elements at least partially formed of concrete, which are rigidly interconnected along their lengthwise sides, and wherein viewed in cross-section, the wall of the lower clement extends outwardly and in an ascending fashion towards the upper element. The invention is also directed to a novel method of fabricating such hollow box supports or girders and the use thereof as structural components. The term hollow box support" or equivalent expressions is intended to encompass box girders, beams or like structural components.

It is a primary object of the present invention to provide a new and improved hollow box support of both increased height and span width, providing a shearresistant and rigid connection between both elements from which it is formed, and wherein with minimum expenditure it is possible to obtain supports having different heights.

Another object of the present invention relates to a new and improved method of constructing such hollow box supports in an economical and reliable fashion, requiring a minimum of operational steps, and resulting in improved production capacity and economies in the fabrication process.

Now in order to implement these and still further objects of the present invention, which will become more readily apparent as the description proceeds, the invention is manifested by the features that a respective essentially upright connection layer formed of concrete is applied to bear against the lengthwise extending sides of both the upper element and the lower element. Reinforcements containing reinforcement elements or members embedded in both the upper and lower elements and extending in the transverse direction with regard to the hollow box support extend into such connection layers and at that location overlap, and wherein the reinforcement layer located at the lower element extends neighboring the outside of the wall of the relevant element.

The method aspects of this development reside in the feature that the lower element is fabricated in an open mold and the pre-fabricated upper element is then placed upon the lower element, and thereafter there is.

cast or molded the connection layers.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a cross-sectional view of a first embodiment of inventive hollow box support;

FIG. 2 is a cross-sectional view of a second embodiment of inventive hollow box support;

FIG. 3 illustrates one possible use of the inventive hollow box support; and

FIG. 4 is a view, similar to FIG. 1, of a modification of the hollow box support depicted in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, the hollow box support depicted in FIG. 1 exhibits a closed cross-sectional configuration and possesses a substantially bowl-shaped lower element 1 formed of concrete and an inverse substantially U-shaped or trough-shaped upper cover or deck element 2 formed of concrete, and which elements 1' and 2 are rigidly interconnected.

The cover element 2 is composed of a cover or deck portion 3 and side walls 4 which connect with both sides of the cover portion 3 and extend in a slightly downwardly diverging direction from both sides of such cover 3. The ends or terminal surfaces 5 of these side walls 4 are slightly inclined upwardly towards the outside, as shown. At two region or zones 6 which are in spaced superimposed relationship with respect to one another there are provided at the outside of the side walls 4 inwardly directed wall sections, by means of which there are formed protruding cams or dogs which have not been further illustrated. At the cover portion 3 of the cover element 2 there is embedded a reinforcement layer or means 7 which extends over the entire width of the cover portion 3 and protrudes at its ends 8 at both sides out of such cover 3. The protruding ends 8 of this reinforcement means 7 extend into a respective cover-and connection layer 9 formed of concrete which bears against the outside at the side walls 4 of the upper element 2. The ends 8 of the reinforcement means 7 located in the concrete layers 9 are flexed or bent downwardly at right-angles.

The reinforcement means 7 is essentially horizontally disposed at the region of the cover portion 3. Further, as a function of the static moment the cover portion 3 is raised or domed at its transverse central region 3a with respect to the reinforcement means 7 and at its lateral end regions 3b is sunk or lowered. There is only present one reinforcement layer 7 have transversely extending rods schematically indicated at 7a.

The bowl-shaped lower element 1 possesses a substantially cylindrical central section 1a with which merge upwardly curved marginal sectionslb which terminate at the outer ends at an angle of inclination which is between 40 and 50 The upper end surface 1c of the wall of the lower element 1 is essentially horizontal and simultaneously forms the joint plane between the elements 1 and 2. The inner edges 4a of the side walls 4 of the upper element 2 coincide with the upper inner edges 1d of the wall of the lower element 1. The wall thickness of the bowl-shaped element 1 is, however, greater than that of the side walls 4 of the upper element 2, so that the wall of the element 1 at the region of the connection location or joint protrudes outwardly with regard to the side walls 4 of the upper element 2, as shown. The concrete layers 9 interconnecting both elements 1 and 2 are flush at their lower ends 9a with the upper outer edges le of the wall of the lower element 1 and extend upwardly where they flushly meet with the cover or deck surface of the cover portion 3 of the upper element 2. The concrete layers 9 gradually become thicker in the upward direction and together with the side walls 4 of the upper element 2 form lateral walls of the hollow box support which are symmetrical with regard to their central plane and become gradually thinner in the downward direction.

The bowl-shaped element 1 is likewise provided with a reinforcement means or layer which at both sides extends upwardly out of the outwardly protruding region of the end surfaces 1c of the wall of such element and into the concrete connection layers 9. Within such layers 9 this reinforcement means 10 extends upwardly to the height of the cover or deck portion 3 of the upper element 2. The upper ends or regions 10a thus overlap with the downwardly flexed ends 8 of the reinforcement means 7 protruding out of the upper element 2 and are disposed externally thereof.

The lower element 1 possesses only a single reinforcement layer or means 10 which is curved in accordance with the curvature ofthe wall of this element and extends in neighboring relationship with regard to the outside surface of element 1.

The reinforcement means 7 and 10 preferably possess rods 7a and 10a respectively, arranged in parallelism at a small spacing from one another, for instance approximately cm., and extend in the aforedescribed manner into the connection layers 9.

Furthermore, the lower element 1 additionally possesses prestressing cables 11. Additional prestressing cables 12 are located at the upper region of the connection layers 9. The lastmentioned cables 12 act upon the entire cross-section of the support.

The upper element 2 is generally prefabricated from concrete in a mold constructed as a jarring or jolting table. The lower element 1 is formed in an open mold by means ofa finisher displaceable along the mold. The lengthwise sides of the mold possesses upwardly extending bowl walls. The upper element 2 is placed upon the lower element 1 still located in the open mold. Thereafter, fresh concrete is filled and vibrated into the intermediate space between the side walls 4 and the aforementioned bowl walls. In so doing, care is taken to ensure that the fresh concrete penetrates into the inwardly directed sections of the side walls 4 and comes to bear against the side walls and the end surfaces of the wall of the lower element 1.

In this way there is obtained a high hollow box support for large span widths possessing a rigid and shearresistant connection between the elements 1 and 2. Furthermore, there is obtained a hollow box support with only a single reinforcement layer which extends about the cross-section or girth of the support and forms a closed frame.

FIG. 2 illustrates a hollow box support which is particularly suitable for the construction of trafficways, such as elevated roadways, bridges and so forth. During the erection of the trafficway a concrete layer 13 is placed upon the deck or top 3 of the upper element 2 which, then, forms the top surface of the roadway of such trafficway. For this purpose reinforcements l4 and 15 are respectively provided at the center region of the deck portion 3 and at the connection layers 9, these reinforcements protrude upwardly and then are horizontally bent over.

FIG. 3 illustrates a cross-section of a bridge in which three inventive hollow box supports 16, 17 and 18 are disposed alongside one another at their longitudinal or lengthwise extending sides. The supports l6, l7 and 18 are mounted completely separately from one another. The supports 16 and 17 each form a longitudinal section of a roadway, whereas the other support 18 forms a longitudinal section of a pedestrian walkway. For this purpose the last-mentioned support 18 is arranged at a higher elevational position than the other supports 16 and 17, so that its side wall functions as a curb 30 for the traffic roadway. The support 18 is inclined slightly towards the outside and downwardly whereas both of the other supports 16 and 17 are inclined slightly towards one another and downwardly.

Of course, as many supports as desired could be joined alongside one another in the lengthwise direction. Within the hollow compartments of the box-like supports there could be housed suitable heating devices, which have not been particularly shown.

The only difference between the construction of support as depicted in FIG. 4 over that shown in FIG. 1 is that in the embodiment of FIG. 4 an additional tension or stress take-up element 20 is arranged approximately at the central region of the height of the support cross-section and which extends substantially perpendicular to the axis of symmetry of such support crosssection. This element 20 extends between both side walls 22 and 23 of the support and penetrates through both elements 1 and 2 into the connection layers 9, at which location there are anchored its upwardly flexed ends 20a by any suitable means. Tension take-up element 20 can be in the form of a sheet-metal plate, the thickness of which and anchoring of its ends being calculated as a function of the loads to be carried. If desired, instead of using a sheet-metal plate there could be provided metal rods arranged at a spacing from one another, for instance formed of steel, and the diameter of which, the mutual spacing from one another and the anchoring of the ends thereof being calculated as a function of the loading thereof. Therefore in FIG. 4 reference character 21 is intended to represent a tension or stress take-up element 20 either in the form of a plate or spaced rods.

The advantage of an arrangement of spaced rods resides in the ability to handle higher support loads inasmuch as the tension take-up element 20 prevents any lateral bending-out of the side walls 22 and 23 of the support. Moreover, element 20 subdivides the inner hollow space or compartment 24 of the support itself into two channels 25 and 26, one of which can serve, for instance, for the introduction of air and the other for the withdrawal of air.

During the production of the hollow box support of the type depicted in FIG. 4 the tension take-up element 20 is placed upon the lower element 1 still located in the open mold, whereupon then the cover of top element 2 is placed thereon and the connection layers 9 are molded or cast. Of course, the hollow box support of the type shown in FIG. 2 could also be provided with one or a number of such tension take-up elements 20.

The described hollow box supports can also be used as ceiling or roof elements. Furthermore, if the concrete connection layer 9 is constructed so as to protrude past the deck or top portion 3 then it is possible to form a trough. Such type support can then advantageously serve as a shed trough at a sawtooth-type roof.

The hollow box supports can be also used as swimming concrete pontoons.

If necessary, the hollow box supports can be closed at both of their end faces, as schematically indicated in FIG. 3 by the closure means designated by reference character 31.

The height of the upper U-shaped element 2 also could be varied in the lengthwise direction of the element and, for instance, could be caused to ascend from both of its end faces towards the center or could ascend from one end face towards the other.

Furthermore, a respective further reinforcement layer for the shear stresses and the main tensional stresses is preferably provided at the region of the end faces of the hollow box support, which reinforcement layer is disposed at the lower structural element and the connection layers and is anchored with the upper structural element.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. ACCORD- lNGLY,

What is claimed is:

1. A hollow box support comprising a reinforced lower structural element at least partially formed of concrete, a reinforced upper structural element at least partially formed of concrete and vertically spaced from the lower element, each of said structural elements having lengthwise extending sides, said lower element, when viewed in cross section extending towards the outside in ascending fashion in the direction of and towards said upper element, concrete side walls extending substantially vertically between said upper and lower elements and rigidly connected to the respective lengthwise extending sides, concrete connection layers respectively rigidly connected to the outsides of said side walls and also extending substantially vertically between said upper and lower elements along the respective lengthwise extending sides, reinforcement means incorporating reinforcement elements provided for said upper and lower elements and extending in the transverse direction of the hollow box support, the ends of said reinforcement means extending respectively into the concrete connection layers at each lengthwise extending side and overlapping one another thereat, with the end of the reinforcement means of the lower element close to the outwardly facing portions of the hollow box support, and wherein said upper element includes a deck portion, reinforcement means being also provided in said deck portion including reinforcement means with ends extending into said concrete connections, said deck portion, viewed in crosssection, being disposed at its central region with regard to said reinforcement means thereof such that it is displaced in offset relationship towards the top and at the marginal ends such as to be offset towards the bottom. l= 

1. A hollow box support comprising a reinforced lower structural element at least partially formed of concrete, a reinforced upper structural element at least partially formed of concrete and vertically spaced from the lower element, each of said structural elements having lengthwise extending sides, said lower element, when viewed in cross section extending towards the outside in ascending fashion in the direction of and towards said upper element, concrete side walls extending substantially vertically between said upper and lower elements and rigidly connected to the respective lengthwise extending sides, concrete connection layers respectively rigidly connected to the outsides of said side walls and also extending substantially vertically between said upper and lower elements along the respective lengthwise extending sides, reinforcement means incorporating reinforcement elements provided for said upper and lower elements and extending in the transverse direction of the hollow box support, the ends of said reinforcement means extending respectively into the concrete connection layers at each lengthwise extending side and overlapping one another thereat, with the end of the reinforcement means of the lower element close to the outwardly facing portions of the hollow box support, and wherein said upper element includes a deck portion, reinforcement means being also provided in said deck portion including reinforcement means with ends extending into said concrete connections, said deck portion, viewed in cross-section, being disposed at its central region with regard to said reinforcement means thereof such that it is displaced in offset relationship towards the top and at the marginal ends such as to be offset towards the bottom. 